1. Field of the Invention
This invention relates generally to electronic reproduction apparatus operable in copier and/or printer modes and more particularly to a copier and/or printer having an interrupt operation wherein plural interrupt jobs may be nested or stacked.
2. Background Art
In U.S. Pat. No. 5,105,283, description is provided of an electrophotographic reproduction apparatus that is operable in both copier and printer modes. As used herein, the term "copier" is meant to refer to apparatus arranged for reading the image information on an original document sheet and for reproducing such image information on a receiver or copy sheet, which is a "hard copy." The term "printer" is meant to refer to apparatus arranged for receiving image information in other than hard copy form, referred to as electronic form, and for reproducing such image information on a receiver sheet. The term "original" is meant to refer to image information to be reproduced, whether such image information is in hard copy, electronic or other form. The term "reproduction apparatus" is meant to refer to copiers and/or printers. The term "print job" is used in its conventional sense and implies operation of the apparatus in a printer mode to produce one or more hard copy sets from a production job requesting printing of data in accordance with predetermined parameters requested for producing said copy sets. The data may represent one or more pages of data. The term "copy job" is used in its conventional sense and implies operation of the apparatus in a copier mode to produce one or more hard copy sets from a production job requiring copying of an original document having one or more hard copy pages in accordance with predetermined parameters requested for producing said copy sets.
A typical job represents a request to either print or copy a page or a sequence of pages. Where it represents a sequence of pages, the pages will be collated as a group or output finished such as by stapling.
In known copier/printer reproduction apparatus, a problem
is associated with management of the copier and printer functions since only one marking engine is available for reproducing the information on the copy sheets. More specifically, a job image buffer memory is available as an interface to a writer for storing in rasterized form the information to be printed or copied. The buffer may, for example, have a capacity for storing image data for printing or copying about 50 pages. In order to speed reproduction of the jobs, it is conventional to store plural jobs in the memory and print them out, one by one. It is known to allow for interruption of a print job or copier in progress to allow access to the apparatus for reproduction of one or more other copy or print jobs.
From U.S. Pat. No. 5,206,735, it is known to provide in an electronic copier having an electronic job queue of copier jobs awaiting printing an interrupt system wherein interrupt jobs to be processed are inserted into a print queue at selected locations in a job file succession that is suitable for printing the interrupt jobs at an earliest logical point and interrupting the print job currently being printed when the printer detects the interrupt job. For example, stopping the current production job may occur at the end of a set in process for a collated production job. Where the current production job is uncollated, stopping occurs when the last print of the page being printed is made.
When processing plural interrupts, the prior art notes that more recent interrupt jobs are restricted such that they are placed in the print queue immediately after the previously programmed interrupt job. Interrupt jobs are then handled on a first-in first-out (FIFO) basis and cannot be reordered.
The inventor has recognized that a copier and/or printer reproduction apparatus having a first-in, first-out hierarchy for nesting of interrupts provides an unforeseen restriction on the available features for reproduction.
It is therefore an objective of the invention to provide a copier and/or printer apparatus with improved handling of plural interrupts.